Indicating-calipers



T. E. GROVE.

INDICATING CALIPERS. APPLICATION FILED MAR-25,1918- Patented J an. 18,1921.

/ ATTORNEY THOMAS E. GROVE, 0F DAYTON, OHIO.

INIJIIIGA'I'ING-CALIPEIRS.

Application filed March 25, 1918.

To all whom it may concern:

Be it known that I, THOMAS E. GRovE, a citizen of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Indicating-Calipers, of which the following is a specification.

My invention relates to measuring instruments and particularly to a micro-indicating caliper. The instrument is designed to indicate slight variations of measurement upon a ma nified scale.

e object of the invention is to improve the construction as well as the means and mode of Operation of such devices, whereby they will not only be cheapened in construction but will be more efiicient in use, automatic in action, reliable in operation and unlikely to get out of repair.

A further object of the invention is to provide improved means for mounting the movable parts of the instrument in such manner as to avoid excessive friction and to reduce resistance and wear of the parts to a minimum.

A further object of the invention is to provide such a device which will-be extremely sensitive to minute variation of measurement without undue vibration or' unsteadiness of the indicator.

A further object of the invention is toprovide a protective mounting for the operating parts, which will not only protect the connection but will exclude dirt, and prevent the accidental disarrangement of the parts.

With the above primary and other incidental objects in view as will more fully appear in the specification the invention consists of the features of construction,the parts and combinations thereof, and the mode of operation or their equivalent, as hereinafter described and set forth in the claims.

In the drawings Figure 1, is a perspective view of the assembled instrument. Fig. 2, is a detail view of the indicating members with the cover or protective cap removed.

Fig. 3, is a detail perspective view of the cover or cap. 1 Fig. 4, is a detail perspective view of the indicator or pointer. Fig. 5, is a detail perspective view of the mounting or connection of the feeler or contact member,

"viewed from the side opposite that shown in Fig. 2;

Like parts are indicated by similar charac- Speciflcation of Letters Patent.

Patented Jan. 18, 1921.

Serial No. 224,510.

ters of reference throughout the several views.

In the drawing the invention has been shown as applied to a caliper for inside measurements. It is to be understood however, that it is equally applicable to outside calipers. Furthermore, while the indicating apparatus has been herein shown and described as applied to the leg of a caliper it is to be understood that the same mechanism might be mounted upon a different support or a different instrument.

The caliper comprises a pair of relatively adjustable legs 1 and 2 connected one to the other by the pivotal head 3. The leg 1, terminates in a fixed or integral contact point 4, which is preferably bent slightly out of the general plane of the leg 1, into a plane common with that of the movable or yielding contact or feeler hereafter described. The extremity of the leg 2, is formed somewhat blunt and adjacent to the end of the leg is pivotally mounted a contact or feeler member 5, consisting of a short outwardly turned arm 6. for engagement with the work and an extended multiplying arm or lever 7 This contact or feeler member is pivoted at 8, upon a stud or screw engaged with the extremity of the leg 2, of the instrument. The pivotal stud 8, of the feeler or contact member engages in an opening in the leg 2, which opening is intersected by a slot or kerf 9, extending from the end of the leg 2. Before hardening and after the hole has been tapped for the pivot stud the kerf or end is compressed-whereby a gripping tension is maintained on the stud. The upper or free end of the contact feeler is formed with a substantially circular head 10. Pivoted upon the leg 2, at a mid length point is an oscillatory indicator or pointer 11, the head of which is bifurcated to receive the head 10, of the contact feeler arm 7. This bifurcation issomewhat elongated and proportioned to receive the head 10, in the contact arm. This construction affords a free working bearing of considerable extent having but littlev lost motion by which the accurate and uniform operation of the device is insured. The head portion of the pointer or indicator is somewhat thicker than the arm thereof thereby reducing the frictional contact surface. The side of the head opposite the bifurcatior. and immediately beneath the pointer or indicator arm, is slotted as at 12 to receive the free end of a flexible hair Spring of fine wire, the opposite end of which is fixedly secured at 13 to the leg 2. The free end of this spring works loosely in the slot 12, and serves to move the pointer or indicator hand and with it the contact or feeler member toward one limit of their stroke, thus, tending to return the parts to normal after each operation and taking up or compensating for any lost motion. The interconncction of the feeler or contact member with the pointer or indicator and pivotal connections of the latter with the leg 2, are inclosed in a housing or cap 15, recessed or notched at diametrically opposite points as at 16, to permit the free movement of the members within. To further reduce the frictional bearing surfaces and to hold the indicator hand or pointer in its proper working plane, the interior of the cap or housing 15, is provided with an internal boss 17. This boss serves to hold the indicator or pointer in its proper plane of oscillation without materially increasing the friction thereon. The free, end of the pointer or indicator plays to and fro within a keeper or loop 18, secured to the leg 2. This keeper or loop limits the oscillation of the pointer hand or indicator in either direction. This keeper or loop is positioned closely adjacent to the end of the pointer or indicator and so protects the accidental. engagement of the pointer with other objects which might bend or break the pointer arm or interfere with its usefulness. Coincident with the keeper or loop is a series of graduations 19, which may be arranged to indicate different degrees of measurement according to the proportion or multiplying power of the movable levers. While any system of marking the graduations may be used it is preferred to mark the middle point zero and number the graduations from this zero point in opposite directions. By this means the mechanic will adjust the caliper to the desired measurement with the pointer at zero. The application of the instrument to the work will then indicate the variation either plus or minus.

From the above description it will be apparent that there is thus provided a device of the character described, possessing the par- I ticular features of advantage before enumerated as desirable but which obviously is susceptible of modification in its form, proportion, detail construction or arrangement of parts, without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute, the invention has been described in language more or less specific as to certain structural features, it is to be understood that the invention is not limited to any specific details, but that the means and construction herein described comprises but one mode of putting the invention into effect, and the invention is therefore claimed broadly in any of its possible forms or modifications within the scope of the appended claims.

Having thus described my invention, I claim:

1. In a measuring instrument, a. pair of inter-connected caliper legs, a contact or feeler member pivoted to the extremity of one of the legs, the engaging end of the contact member being short and laterally turned the opposite arm of the member being extended in the general direction of the supporting leg and terminating in a substantially circular head an indicator arm the pivotal head of which is of greater thickness than the arm, said head being bifurcated to receive the substantially circular head of the contact or feeler arm, the side of said head opposite the bifurcation being slotted, a fine wire spring one end of which is fixedly attached to the supporting leg the free end being engaged in the said slot and a cover cap inclosing the said head and its interconnections, said supporting leg bearing a series of graduations with which the indicator arm co-acts.

, 2. In a measuring insti-nnent, a supporting member, a pivoted indicator member mounted thereon, an offset or shouldered head at the pivotal end of said indicator member and a pointer ham extending therefrom, said offset head having a slot therein immediately beneath the extended hand of .said indicator, a section of spring wire one end of which is fixedly attached to said support, the free end of which engages in the said slot, said indicator member being movable about its pivotal connection against the tension of said spring, and a contact or feeler member engaged with the indicator member adapted by its movement to actuate the indicator member.

3. In a measuring instrument, a support, a contact or feeler member pivoted to the support, comprising a work engaging arm and a movement multiplying arm, a pivoted indicator member having a bifurcated head in which said multiplying arm engages and an extended indicating arm co-acting with a series of graduations upon the support to indicate the degree of movement of the contact or feeler member, a circular cap or housing inclosing the interconnections of the contact or feeler member with the indicator member and that of the indicator member with the support, the peripheral walls of the housing being cut away at diameterically opposite sides to permit the movement of the inclosed members, the interior top of said cap or housing having a central boss,

and a pivotal stud extending through said boss and the head of the indicator member and engaging in the support.

4:; In a measuring device the combination fixedly connected to the supporting structure 10 with a supporting structure, a movable conat one end and loosely engaging in said re tact member and a pivoted indicator 0pcess, substantially as specified. eratively connected with the movable contact In testimony whereof, I have hereunto set member, of an offset formed on the indicator my hand this 9th da of March, A. D. 1918.

adjacent to the pivotal connection thereof T OMAS E. GROVE. on the side of said indicator adjacent to the Witnesses: supporting structure, said offset having a JOHN DINEEN,

recess formed therein, and a spring finger F. L. WALKER. 

